Design of multimaterial processed by powder metallurgy: Processing of a (steel/cemented carbides) bilayer material

A bimaterial, consisting of tough and hard layers, was designed to be processed by powder metallurgy. A materials selection software lead to choose steel and cemented carbide for the tough and hard components. To insure the interlayer compatibility, Fe was selected as base of the tough part and as binder of the hard part. The compositions and the temperature range enabling the simultaneous consolidation of the Fe base by transient liquid phase sintering and of the WC base by liquid phase sintering were defined from thermodynamics data. Experiments lead to define a treatment in two steps: presintering (1080 °C) for the partial densification of the Fe base then sintering (1280–1320 °C) to achieve densification and cohesion of the bimaterial. The sintering temperature increase provided a higher liquid fraction leading to interface cohesion but coarse porosity development. Bimaterial, with fair mechanical properties, were obtained by presintering at 1080 °C then sintering at 1280 °C.